An efficient access to 6-substituted 7-deazapurine and the corresponding nucleosides by coupling aryl or alkyl Grignard reagents and halogenated purine nucleosides in the presence of Fe(acac)3/CuI is described. A series of 6-substituted 7-deazapurines and the corresponding nucleosides were obtained in medium to good yields. For the synthesis of modified nucleosides that will be the subject of biological testing, we propose to use iron-catalyzed instead of palladium-catalyzed reaction. The synthesized compounds were tested for their antiproliferative activity. The cytotoxicity study of compounds 11a-q shows that by modifying the 6-position of 7-deazapurine ribonucleosides, the compounds may become selective for certain cancer cell lines.